Politics of the US America takes place in a framework of a presidential republic, where by the President of the United States is head of state, head of government, and of a de facto two-party legislative and electoral system. The federal government shares sovereignty with the state governments, with the Supreme Court balancing the powers of each.The executive branch is headed by the President and is independent of the legislature. Legislative power is vested in the two chambers of Congress, the Senate and the House of Representatives. Judicial power is exercised by the judicial branch (or judiciary), composed of the Supreme Court and lower federal courts. The judiciary's function is to interpret the United States Constitution as well as the federal laws and regulations. This includes resolving disputes between the executive and legislative branches. The federal government of the United States was established by the Constitution. American politics has been dominated by two parties, the Democratic Party and the Republican Party, ever since the American Civil War, though other parties have also always existed.
Major differences between the political system of the United States and that of most other developed democracies are the power of the Senate as the upper house of the legislature, the wide scope of power of the Supreme Court, the separation of powers between the legislature and the executive government, and the dominance of the two main parties - the U.S.A being one of the world's developed democracies in which third parties have the least political influence.